We address tactical behaviors of unmanned ground vehicles (UGVs) and focus on their coordination within hierarchical units. This research thus addresses multiagent systems but more particularly structures where autonomous parts coordinate to form wholes that in turn are parts in more inclusive wholes. To capture these notions, we introduce the concept of a holarchy (a hierarchy of holons, which are both parts and wholes) and use an enhancement of the Statechart notation called Parts/whole Statecharts. We relate aspects of this notation to the technical notion of common knowledge, which is a necessary condition for coordination, and we sketch techniques for building holarchic models using Parts/whole Statecharts. An implementation of one such model in Matlab’s Stateflow tool is sketched.